<Page
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Page.Resources> 
    <Style TargetType="Button" x:Key="BlackButton"> 
      <Setter Property="Background" Value="Black" /> 
      <Setter Property="Foreground" Value="White" /> 
    </Style>
    
    <Style TargetType="Button" BasedOn="{StaticResource BlackButton}"> 
      <Setter Property="Foreground" Value="Red" /> 
    </Style>
  </Page.Resources>
  <StackPanel>  
      <Button Content="button1" Style="{StaticResource BlackButton}"/> 
      <Button Content="button1" /> 
      <Button Content="button1" /> 
      <Button Content="button1" />       
  </StackPanel>
</Page>